Catheter introducers in percutaneous procedures are placed in a vein or artery of a patient in accordance with various procedures known in the art. A catheter introducer typically includes a long sheath that has a distal end positioned in the vein or artery and a proximal end positioned immediately external to the epidermis. The catheter introducer also includes a valve assembly positioned at the proximal end of the sheath. After the catheter introducer is mounted in accordance with the insertion procedure, generally several catheter tubes are exchanged, one replacing the other, each one being passed through the catheter introducer into the vein or artery and thereupon directed by the doctor to its final destination.
A primary concern prior to the insertion of the catheter tube into the catheter introducer both during the time the catheter tube is positioned in the introducer and after the removal of the catheter tube from the introducer is blood loss, and more particularly excessive blood loss.
One type of introducer valve assembly includes two valves. This type is described in U.S. application Ser. No. 760,817, filed Jul. 31, 1985, entitled "Self-sealing Percutaneous Tube Introducer", allowed on May 14, 1986. The first internal valve seals off any passage of blood from the sheath of the introducer during the time the catheter tube is not present in the introducer. The second external valve seals around the catheter tube during and after the insertion of the catheter tube into the introducer so as to seal off any passage of any blood present in the sheath around the outer surface of the catheter tube. The second valve is typically a valve with a small thru-hole.
This invention is directed to the first valve. The first valve is directed to accomplishing the primary purpose of shutting off the flow of blood in the sheath when the catheter tube is absent, but it must also be adapted to easily allow passage of the catheter tube during the insertion procedure. These two functions are fundamentally contrary and thus present a basic problem.
The introducer described in U.S. application Ser. No. 760,817 has the first and second valves in the valve assembly placed upstream and downstream, respectively, relative to the blood flow, that is internally and externally with respect to the patient. The first valve is made of a resilient, flexible material such as rubber and has three triangularly configured slits meeting at the axis of the valve forming three flaps. The slits easily open as the catheter tube is passed through the introducer during the insertion procedure, and further resiliently close to shut off any blood flow when the catheter tube is not present. Although the triangular flaps close off the interior of the introducer valve assembly when the catheter tube is not present, it can be said that the closing of the triangular shaped flaps is somewhat imperfect against the pressure of blood escaping from the vein or artery, so that some leakage of blood can occur.